Hey All! I’m brand new here and brand new to fiberglass, so I have a beginner’s question. I was reading on some boat building forums the gelcoat will not adhere to epoxy. That being said, do I have to use polyester resin when making a mold (due to applying gelcoat to the mold)? Also, if I am starting out with a layer of gelcoat for my part, can I use epoxy? I would like to use epoxy if possible due to less fumes and toxicisty.
I hope this makes sense. Any help would be greatly appreciated.
-Jim
You have to sand the gelcoat and then it will work. But why not using an epoxy gelcoat?
Also choose what kind of finish you would like on your parts. If you will sand and paint them afterwards, the quality of finish of your gelcoat is less crititcal, and you can get away with a layer of slightly thickened laminating epoxy as a gelcoat for your tool.
I would like to start making some custom motorcycle parts, so they will certainly be sanded and painted. I apologize for not understanding, but I’m still learning here- when you say using laminating epoxy for the tool, are you referring to the plug, mould, or final part?
Jim,
Epoxy is no less “toxic” than than polyester or vinylester. Epoxy is a sensitiser. It is even more important to avoid getting it on your skin, or inhaling it’s dust, than PE or VE.
‘tool’ usually refers to the mold.
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Thanks for the heads-up. I was under the impression it was less toxic. I will be doing all of my work outside and with a mask regardless.
As a newbie, I would suggest using a proper epoxy gelcoat if you choose to use epoxy. I’ve thickened my resin to use as a gelcoat, but trial and error has made it very timely, expensive and inefficient. I’ve gotten bubbles, inconsistent thickness, inconsistent viscosity…I would just buy a proper gelcoat.
Most recently, I have used AdTech ES 218 Sandable Surface Coat Resin. I am going to de-mould in the next hour or two, so I will not know the final results until then. I have also used FiberGlast High Temp Epoxy Surface Coat 1096, which is a really good product, but that stuff is expensive.
Next on the list is PT&W, not because I am dissatisfied, but only because a member on the site recommended them to me. I have seen some things that he has built and his quality says everything.
The opposite is true. The distributors of epoxy will tell you to take the same precautions as for PE and VE. What they don’t tell you is that failure to follow those precautions can have more severe consequences with epoxy compared to other resins. I am not knocking epoxy. I work with both epoxy and vinylester on a daily basis.
IMEDGE ECT 120 by CCP
www.compositesworld.com/products/gel-coat-for-epoxy-infusion. I have never used it but it sounds like what you are looking for.
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Smooth-On carries epoxy tooling resins. They have a red or grey gelcoat and also a laminating tooling resin.
The epoxy is very affordable.
The gelcoat is very forgiving of mistakes and can be repaired easily.
The only downside is it is very tough to polish it to any kind of gloss. The best is what I would call a sanded finish. The high Class A finish seen sometimes on polyester tooling is probably not achievable with this resin system.
Other than that it works great.
Interesting! I just tried an epoxy test on a small part this afternoon - ultimately for a part that requires dramatic wear resistance. I took some Fibreglast 2000 epoxy, added silica carbide and black tint and the surface (treated as gel coat) has hardened to what I believe to be a suitable one. The bad news was that hand lay-up took a while. The epoxy has a working time of 20 minutes and took about 35 to get to a thick enough gel to stick to the convex walls of mold (though I am still experimenting with mold releases). I added 2 layers of CF cloth and brushed on untreated epoxy 2000. The abrasion resistance is what I am after and a lot better than the West System (shore 83 vex shore 88 of system 2000). On the other hand, I hope to have a more efficient process (spray gun? fast dry in thin layers? The parts are relatively small and wonder if a prevail would work? I do have a compressor but, you know…) Any ideas? PS - I am also looking for a degree of lubricity and am wondering if a small amount of PTFE can be mixed in?